The invention relates to a device and method of using the device for providing a suspended volume of an agent without additional mixing.
Agents that do not persist in a suspended state and sediment must be resuspended prior to use. One example of an agent that must be resuspended prior to use is a pharmaceutical colloid, such as a contrast agent that is injected into a patient to enhance an imaging procedure. Contrast agents are used in various types of imaging including x-ray, magnetic resonance imaging (MRI), computed tomography (CT) and ultrasound (US). A contrast agent that comes out of suspension must be resuspended before placing the desired volume to be dosed into a delivery container such as a syringe. If there is a delay before the dose is injected into a patient, for example while preparing the patient or equipment, or if the infusion is extended, the agent must again be suspended before or during administration.
Resuspension of contrast agent requires mechanical manipulations, for example, removing a filled syringe positioned in an injector and remixing its contents. Additional remixing steps may delay a critical infusion time or, if remixing is omitted, the entire imaging procedure may have to be repeated due to suboptimal contrast obtained. Duplicate procedures not only put patients at increased risk and inconvenience, but are also cost- and time-inefficient. Even if the need to resuspend a single bolus injection is not prohibitive for a given procedure, repeated bolus injections or long term continuous infusions can become problematic due to agent coming out of suspension during administration.
The loss of suspension for a contrast agent at any point in a delivery system to a patient, such as in a syringe and/or in the connecting tubing, severely limits the duration of continuous infusions or the time between intermittent injections. The need to initially resuspend the colloid or other type of agent, and to further suspend if the agent is not used shortly after resuspension, requires either time-consuming effort and vigilance by the user or the use of mechanical mixing devices. In any case, the need to resuspend an agent poses an additional step and a possible source of error in an imaging procedure.
The invention is directed to a device that provides a suspended agent without additional mechanical mixing. The device divides a total volume of a sedimenting agent into a network of sub-volumes and has ports for an inflow and outflow of a propellant fluid to release the sub-volumes of agent from the device. In one embodiment, the device is located within a container in which the agent is packaged, such as a vial or bottle, or in a container in which the agent is dosed, such as a syringe or bag, or in a container containing the propellant fluid. In another embodiment, the device is located external to a container for the propellant fluid. In this embodiment, the device may be operably attached to an exit port of the propellant fluid container. Alternatively, in this embodiment, the device may be positioned in-line at any point with lines that connect the propellant fluid container with a patient connector. The device is comprised of a network of sub-volumes that may take the form of one or more tubes, cells and/or sponges, and that may assume any configuration such as a parallel, stairstep, helical, random and/or coiled configuration. The network may be retained in a network holder.
The invention is also directed to a suspension device for a volume of an agent in which a container for the propellant fluid has a network of grooves that are integral with the container and that retain a sub-volume of the agent within the grooves. The container has a plug that occupies an internal volume of the container and the grooves are either integral with an internal wall of the container, or are integral with an external wall of the plug. In either embodiment, the plug diverts the propellant fluid flow to a variable extent from the center of the container to the periphery of the container, thus diverting fluid flow through the grooves. The grooves may further contain substantially perpendicular channels at regular intervals to allow uniform filling of the grooves with the agent.
The invention is also directed to a method of providing a volume of suspended agent to a patient. The method includes dividing the volume of agent into contained sub-volumes, storing the sub-volumes in a network for containing sub-volumes of the agent and providing a propellant fluid under pressure to eject the sub-volumes of agent through the network and into a patient. The propellant fluid may be housed in a container in which the network is also located. Alternatively, the network may be external to the propellant fluid container, with the network positioned either in-line between a source of propellant fluid and a patient, or adjacent an exit port of a propellant fluid container.
The invention is also directed to a suspension device for a volume of an imaging contrast agent. A network contains a plurality of sub-volumes of the agent and has inflow and outflow ports for propellant fluid. The device may also have a container and network holder external to the container.
The objectives and other advantages of this invention will be further understood with reference to the following drawings and detailed description.